Typehead support for a single element printer

ABSTRACT

A typehead for a single element printer is rotatably supported on a support member which is pivotable to enable the print head to be rotated and tilted for positioning a selected type character for printing. Printing is effected by moving the support member from a rest position to a printing position to impact the selected type character against a cylindrical platen. To prevent smearing or blurring of the printed type character, the support member has a projecting abutment acting against a lower edge of the typehead for precluding a downward tangential movement of the typehead resulting from a component of the impacting force.

United States Patent Decker Dec. 9, 1975 [54] TYPEHEAD SUPPORT FOR A SINGLE 3,247,941 4/1966 Beattie et a1 197/55 ELEMENT PRINTER 3,286,806 11/1966 Sch0enfelder.... 197/16 3,406,807 10/1968 Sasaki et a1 1 197/55 Inventor: Herbert Decker, f, rm ny 3,618,735 11/1971 Bleau 197/55 x [73] Assignee: Triumph Werke Nurnberg A.G.,

N b Gel-many Primary Examiner-Robert E. Bagwill Assistant ExaminerEdward M. Coven [22] Flled: 1973 Attorney, Agent, or Firm-Joseph R. Spalla [21] Appl. No.: 350,523 44 Published under the Trial Voluntary Protest [57] ABSTRACT Program on January 28, 1975 as document no. A typehead for a single element printer is rotatably B 350,523. supported on a support member which is pivotable to enable the print head to be rotated and tilted for posi- [30] Foreign Application Priority Data tioning a selected type character for printing. Printing Apr. 15, 1972 Germany 2218310 is effected y moving the pp member from a rest position to a printing position to impact the selected 521 US. Cl. 197/55 yp Character against a Cylindrical p To Prevent [51] Int. Cl. B41J 7/08 smearing 0T blurring of the Printed yp Character, the [58] Field of Search 197/16, 21, 52, 55 pp member has a projecting abutment acting against a lower edge of the typehead for precluding a 5 R f e Cited downward tangential movement of the typehead resulting from a component of the impacting force.

4 Claims, 2 Drawing Figures US. Patent Dec. 9, 1975 Sheet 1 0f 2 3,924,726

US. Patent Dec. 9, 1975 Sheet 2 of2 3,924,726

VIII

Fig-4 TYPEHEAD SUPPORT FOR A SINGLE ELEMENT PRINTER This invention relates to a single element printer, and more particularly to a support arrangement for the type carrier of a single element printer.

In a single element printer, a plurality of type characters are typically disposed in circumferential rows on a spherical or barrel-shaped type carrier, hereinafter referred to as a typehead, which is hollow and supported by a member received therein. The typehead is supported for rotational and tilting movements to position a selected type character for printing, and printing is effected by moving the support'member from a normal rest position to a printing position to impact the se lected type character against a cylindrical platen. However, when the selected type character impacts against the platen, a component of the impacting force tends to drive the typehead downwardly and tangentially to the cylindrical platen thereby smearing or blurring the printed type character.

In the past, the typeheads of single element printers have been provided with support arrangements having a support member which'acts radially against thetypehead, as shown'for example in German Disclosure Nos. 1,436,690 and 2,055,924. However, such radial supports have not prevented the.undesirable movement of the typehead which resultsfrom a component of the impacting force. Moreover, the typehead must be slightly deformed by the impacting force for a radial support to be effective, and the necessary deformation is precluded in the printing of type characters in the upper rows since the typehead is conventionally supported for rotation at the upper portion of the typehead which is usually reinforced for that purpose.

Accordingly, an object of the present invention is to provide a support for the typehead of a single element printer which prevents the downward movement of the typehead upon impacting against a platen.

Still other objects, features and advantages of the present invention will become apparent to those skilled in the art from the reading of the following detailed description of the invention, taken in conjunction with the accompanying drawing, wherein:

FIG. 1 is a partial diagrammatic view of a single element printer constructed in accordance with the present invention and illustrating the impacting of a type character against a platen;

FIG. 2 is a sectional view taken along the lines 22 of FIG. 1,

FIG. 3 is a partial diagrammatic view of a single element printer similar to FIG. 1 and illustrating an alternative embodiment of a support for the typehead; and

FIG. 4 is a sectional view taken along the lines 4-4 of FIG. 3.

Referring now in detail to the figures of the drawing, there is shown a single element printer, generally indicated 11, for printing type characters on a recording medium, not shown, which may be suitably located on a cylindrical platen 13. The type characters, generally indicated 15, are formed on a sherical or barrel-shaped typehead 17 which is carried on a support means, generally indicated 19, for movement from a normal rest position to a printing position at the platen 13. As is conventional, printing is effected by impacting a se' lected type character against the platen 13, and the typehead 17 may be driven in a printing movement by a suitable drive means, not shown, acting on the support means 19. To enable a line of type'to be printed, the support means 19 is mounted on a carriage 21 for movement past the platen 13. The recording medium and the means for driving the typehead 17 in a printing movement as well as other portions of the printer are not shown since they form no part of the present invention and may be desirably conventional.

As shown, the typehead 17 is generally in the form of an inverted cup having a cylindrical wall 23 and supported at a top portion 25 by the support means 19. The typehead 17 is rotatably supported on the support means 19 by a bolt 27 which is received through a cylindrical opening 29 in the top portion 25 of the type head 17 and secured to a support member 31 which is received in the opening defined by the cylindrical wall 23 of the typehead 17. The support member 31 is pivotally supported on the rocker 33 by suitable bolts 35 for enabling a typehead 17 to be tilted relative to the platen 13, and the rocker 33 is pivoted on the carriage 21 for enabling the typehead 17 to undergo a printing movement to impact a selected type character 15 against the platen 13. The carriage 21 is supported for movement along the platen 13 by a shaft 37 which extends generally paralle'l to the platen 13 andis slidably received through an opening 39 formed in the wall of the carriage 21. In addition, a guide rail 41 is slidably received between a pair of flanges 43 formed on the wall of the carriage 21.

As is conventional, the type characters 15 are disposed on the typehead 17 in circumferential bands or rows 45 which-are generally concentric with the axis of rotation of the typehead 17 and spaced apart axially from each other. To position a selected type character 15 for printing, the typehead 17 may be moved by suitable rotating means, generally indicated 47, and tilting means, generally indicated 49. As shown, the rotating means 47 may be in the form of a pulley 51 secured to the end of a shaft 53 for rotating the typehead 17 in a conventional manner, and the tilting means 49 may be in the form of an arm 55 secured as at 56 to the support member 31 for enabling pivotal movement about axis 35. To finally and correctly position the typehead 17 for impacting a selected type character 15, suitable detent formations are provided which correspond to the rotational and elevational positions of the type characters 15 on the typehead 17. As shown, the detent formations corresponding to the rotational positions of the type characters 15 are in the form of ratchet teeth 57, located inside the typehead 17 on the internal side of the wall 23 and extending parallel to the axis of rotation of the typehead 17. The detent formations corresponding to the elevational positions of type characters 15 are in the form of indentations 59 on the support member 31. Since detent formations and the manner in which they are used to correctly position the typehead 17 for printing are well-known, no further explanation or description thereof is believed necessary.

As previously discussed, when a selected type character 15 impacts against the platen 13, the impacting force has a component which acts on the typehead 17 in a downward in a direction tangential to the cylindrical platen 13. This downward force, resulting from the support of the type carrier at the top portion 25, is illus trated in FIG. 1 by the arrow A and tends to cause smearing of the printed type character.

In accordance with the present invention, the smearing of the printed type character is avoided by providingthe support means 19 with an abutment for resisting the downward component of the impactingforce. As shown, the support member 31 has an abutment in the form of a projection 61 extending radially, and circumferentially adjacent the inner wall 23 of the typehead 17 at the printing position. The ratchet teeth 57 which extend parallel to the axis of rotation of the typehead 17 have a lower edge 63 which is separated from the projecting abutment 61 by only a narrow air gap. Accordingly, when the typehead l7 impacts against the platen 13, the projecting abutment 61 engages the lower edge 63 of the ratchet teeth 57 so as to prevent the downward movement of the typehead 17 by the component A of the impacting force.

Although the projecting abutment 59 is illustrated and described as acting on a lower edge 63 of the 4 support means pivotally supporting said support member for tilting movement to position a selected row of type characters opposite said platen, said support means being movable from a rest position to a printing position to impact a selected type character against said platen,

said typehead on impact experiencing deformation with the lower portion tending to move tangentially relative to said platen and support member,

said lower portion of said typehead having edge defining means located in a radial plane,

and said support member having a radially extending abutment located opposite said platen and located closely beneath said edge defining means for arresting tangential movement of said typehead relative to said platen and said support member on impact of a selected type character against said platen.

2. In a printer as recited in claim 1, said support member having detent formations thereon to finally position a selected row of type characters.

3. In a printer as recited in claim 1, said edge defining means comprising the bottom edge-of said typehead.

'4. In a printer as recited in claim 1, said lower portion of said typehead having internal detent formations corresponding to columnar positions of said typehead to finally position a selected column of type characters, the ends of said detent formations comprising said edge defining means, and said abutment having an arcuate portion located beneath the ends of said detent formations. 

1. In a single element printer comprising a hollow inverted cup shaped typehead having type characters on its outer periphery located in rows and columns, a platen, a support member axially supporting said typehead for rotational movement to position a selected column of type characters opposite said platen, support means pivotally supporting said support member for tilting movement to position a selected row of type characters opposite said platen, said support means being movable from a rest position to a printing position to impact a selected type character against said platen, said typehead on impact experiencing deformation with the lower portion tending to move tangentially relative to said platen and support member, said lower portion of said typehead having edge defining means located in a radial plane, and said support member having a radially extending abutment located opposite said platen and located closely beneath said edge defining means for arresting tangential movement of said typehead relative to said platen and said support member on impact of a selected type character against said platen.
 2. In a printer as recited in claim 1, said support member having detent formations thereon to finally position a selected row of type characters.
 3. In a printer as recited in claim 1, said edge defining means comprising the bottom edge of said typehead.
 4. In a printer as recited in claim 1, said lower portion of said typehead having internal detent formations corresponding to columnar positions of said typehead to finally position a selected column of type characters, the ends of said detent formations comprising said edge defining means, and said abutment having an arcuate portion located beneath the ends of said detent formations. 